Kidneys and glomerular filtration rate

Glomerular Filtration Rate [GFR]: How to Calculate it

A patient with low glomerular filtration rate [gfr] getting dialysis
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What is glomerular filtration rate or GFR?

GFR, or glomerular filtration rate, is a measure of how well your kidneys are working. It’s the most accurate way to measure the level of kidney function and is used to diagnose chronic kidney disease (CKD).

The normal range for GFR is 90 or above, and it’s calculated by measuring the amount of creatinine in your blood.

Creatinine is a waste product produced by your muscles, and the kidneys filter it out of your body.

Another waste product – Cystatin C levels, a more reliable test, is also used to measure GFR.

If your GFR is lower than 90, it could mean that your kidneys are having trouble filtering out the waste, which can be a sign of kidney disease.

Understanding GFR is important for anyone with kidney disease, since it can help you keep track of your condition and how it’s changing over time.

It’s also a useful tool for your doctor to make sure you’re getting the right treatment for your condition. So if you’re worried about the health of your kidneys, make sure you ask your doctor about getting your GFR checked!

Useful resource-


Importance of GFR-

Checking your GFR, or glomerular filtration rate, is an important part of keeping your kidneys healthy. The GFR is a measure of how well your kidneys are functioning — the higher the number, the better.

A low GFR can be an indication of kidney disease, including chronic kidney disease (CKD).

If left unchecked, CKD can cause serious health complications like anemia, electrolyte imbalance, and even heart failure. Therefore, it’s important to have your GFR checked regularly — your doctor can tell you how often you should do this.

If your GFR is low, your doctor will discuss your treatment options. Regular monitoring and treatment of your GFR can help to slow the progression of CKD and improve your overall health.

So don’t wait — get your GFR checked today and take the steps to keep your kidneys healthy!

Calculation of GFR in CKD

GFR (glomerular filtration rate) is a measure of how well the kidneys filter waste from the blood.

It can be calculated using a formula that considers age, gender, and creatinine levels or Cystatin C levels in the blood.

There are different formulas with which you can calculate your GFR. The most commonly used are-

  • Cockcroft-Gault equation
  • Modification of Diet in Renal Disease (MDRD) equation
  • Chronic Kidney Disease Epidemiology Collaboration equation (CKD-EPI)
  • Bedside Schwartz equation

One very easy and simple method is given below-

The formula is: GFR = (140 – age) x (weight) / (72 x serum creatinine)

Alternately, you can download an app that measures GFR on your mobile phone from Google Playstore. You can download the National Kidney Foundation eGFR app here- link. Just put in your Renal profile values along with your age, weight and gender to calculate your GFR.

What should be the normal levels of tests done in Renal Profile-

Use these test report levels as a reference to compare with your actual renal profile test reports and then calculate your GFR using the above-mentioned methods-

  1. Creatinine: 0.7-1.3 mg/dL
  2. Cystatin C: 0.7-1.1 mg/L
  3. Blood Urea: 8-25 mg/dL
  4. Blood Urea Nitrogen: 8-20 mg/dL

GFR in different stages of kidney disease

GFR is an important indicator of kidney health. It shows how much blood is being filtered by your kidneys each minute.

A high GFR means that your kidneys are filtering a lot of blood and your kidney health is normal. However, in chronic kidney disease, GFR is reduced due to kidney damage. Knowing the gfr in different stages of kidney disease is essential for proper diagnosis and treatment.

  • In Stage 1, GFR is above 90 milliliters per minute, which indicates normal kidney function.
  • In Stage 2, GFR is between 89 and 60 milliliters per minute, which indicates a mild decline in kidney function.
  • In Stage 3, GFR is between 59 and 30 milliliters per minute, which indicates a moderate decline in kidney function.
  • In Stage 4, GFR is between 29 and 15 milliliters per minute, which indicates a severe decline in kidney function.
  • Lastly, in Stage 5, GFR is below 15 milliliters per minute, indicating complete or near-complete kidney failure. This is also known as End-stage kidney failure.
  • Knowing your GFR can help you to understand the severity of your kidney condition and take the necessary steps to protect your health.
Different stages of kidney failures and their glomerular filtration rate
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Having learned what is GFR and how to calculate it, it’s time for you to calculate it and learn to keep your kidneys healthy. It also helps you to determine whether you need active treatment by your nephrologist or only lifestyle changes to keep your other measurements like BP and weight is enough.